// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef NET_DNS_ADDRESS_SORTER_POSIX_H_
#define NET_DNS_ADDRESS_SORTER_POSIX_H_

#include <map>
#include <vector>

#include "base/macros.h"
#include "base/threading/non_thread_safe.h"
#include "net/base/address_list.h"
#include "net/base/ip_address.h"
#include "net/base/net_export.h"
#include "net/base/network_change_notifier.h"
#include "net/dns/address_sorter.h"

namespace net {

class ClientSocketFactory;

// This implementation uses explicit policy to perform the sorting. It is not
// thread-safe and always completes synchronously.
class NET_EXPORT_PRIVATE AddressSorterPosix
    : public AddressSorter,
      public base::NonThreadSafe,
      public NetworkChangeNotifier::IPAddressObserver {
public:
    // Generic policy entry.
    struct PolicyEntry {
        // IPv4 addresses must be mapped to IPv6.
        unsigned char prefix[IPAddress::kIPv6AddressSize];
        unsigned prefix_length;
        unsigned value;
    };

    typedef std::vector<PolicyEntry> PolicyTable;

    enum AddressScope {
        SCOPE_UNDEFINED = 0,
        SCOPE_NODELOCAL = 1,
        SCOPE_LINKLOCAL = 2,
        SCOPE_SITELOCAL = 5,
        SCOPE_ORGLOCAL = 8,
        SCOPE_GLOBAL = 14,
    };

    struct SourceAddressInfo {
        // Values read from policy tables.
        AddressScope scope;
        unsigned label;

        // Values from the OS, matter only if more than one source address is used.
        unsigned prefix_length;
        bool deprecated; // vs. preferred RFC4862
        bool home; // vs. care-of RFC6275
        bool native;
    };

    typedef std::map<IPAddress, SourceAddressInfo> SourceAddressMap;

    explicit AddressSorterPosix(ClientSocketFactory* socket_factory);
    ~AddressSorterPosix() override;

    // AddressSorter:
    void Sort(const AddressList& list,
        const CallbackType& callback) const override;

private:
    friend class AddressSorterPosixTest;

    // NetworkChangeNotifier::IPAddressObserver:
    void OnIPAddressChanged() override;

    // Fills |info| with values for |address| from policy tables.
    void FillPolicy(const IPAddress& address, SourceAddressInfo* info) const;

    // Mutable to allow using default values for source addresses which were not
    // found in most recent OnIPAddressChanged.
    mutable SourceAddressMap source_map_;

    ClientSocketFactory* socket_factory_;
    PolicyTable precedence_table_;
    PolicyTable label_table_;
    PolicyTable ipv4_scope_table_;

    DISALLOW_COPY_AND_ASSIGN(AddressSorterPosix);
};

} // namespace net

#endif // NET_DNS_ADDRESS_SORTER_POSIX_H_
